This invention relates to warewashing machines, and more particularly to a chemically sanitizing rinse system which is particularly adapted for use in continuous duty warewashing machines such as conveyorized warewashers.
The inventions set forth in U.S. Pat. Nos. 4,142,539, 4,147,558, 4,147,559 and 4,209,343, all assigned to the assignee of the present invention represent major advances in energy saving chemically sanitizing warewasher technology. By air pumping and transporting the sanitizer (such as liquid sodium hypochlorite), by preparing the rinse solution in discrete batches, and by using the additional features taught therein, as appropriate, such as separately introducing the fresh rinse water and the concentrated sanitizer into a tank where dilution then takes place, the use of a rinse solution mixing tank which is separate from the wash and/or rinse chamber, the use of an independent rinse solution pump, and so forth, significant and important improvements in serviceability, reliability, and durability have been realized. Long felt needs extending over several decades have finally been met.
A review of the above-noted patents, however, will show that they are all directed to what may be termed "stationary rack" warewashing machines. By "stationary rack" is meant a machine in which the rack of dishes or other foodware is inserted and then left in a single or stationary position while the machine subjects it to consecutive washing and rinsing operations at that location. Some machines can hold several racks at once, but the distinguishing feature is that the racks remain stationary and the several washing and rinsing operations are all performed without movement of the rack. At the end of the machine cycle the rack is removed.
With respect to the above-noted applications, it will be appreciated that since the machine cycles are sequential, there is time during some portion of each machine cycle to prepare a batch of chemically sanitizing rinse solution. Also, the amount of solution needed per cycle, and the specific time at which the solution will be needed, are always predictable.
In larger commercial machines, however, this is unfortunately not always the case. Conveyor-type warewashing machines advance the dishes, either individually or in racks, and either continuously or intermitently, through several specialized work stations within the machine. At one location the dishes are washed, and at a later location rinsed. To these may be added a preliminary prewash, a subsequent drying stage, and so on. A machine "cycle" is therefore rather difficult to define. Dishes simply enter the machine at one end, at spacings which vary according to load demand, and exit from the opposite end some time later. During this passage, some or all of the work stations may either be operating continuously or be actuated in response to movement of the dishes or other foodware items therethrough. During periods of intense utilization, the operation of the various stations which are actuated in response to the movement of dishes through the warewasher can be virtually continuous for long periods of time.
In comparison with the stationary rack systems shown in the above-noted patents, it can be seen that a conveyorized warewashing machine requires a rinse system which can provide the chemically sanitizing rinse solution as needed. Since one cannot rely upon a predictable dwell period for preparing the rinse solution, the above-noted batch rinsing processes would appear to be inappropriate for conveyorized warewashers. This would be an unfortunate limitation since the significant advantages of the above-noted inventions, and the considerable energy saving potential thereof, would be especially valuable in these larger size and larger capacity conveyor-type warewashing machines.
A need thus remains for a system and method which provide a chemically sanitizing batch rinse system for warewashing machines which operate on a continuous duty or demand basis in which there may be no defined cycle portion for preparing a batch of chemically sanitizing rinse solution.